What better way for the government to celebrate its new low-carbon revolution than overseeing a major renewable energy scheme for a highly successful factory producing some of the latest fuel-efficient cars?

A win-win for the UK, you might think, with the potential for the country to become an exporter of the very latest in hybrid petrol/electric vehicles from a Toyota plant powered by the sun.

The world's biggest carmaker has applied for planning permission and wants to install 17,000 solar panels, making it one of the biggest projects of its kind in Britain.

The only problem is it is not likely to happen. The solar subsidy regime introduced by ministers in a blaze of glory last year is about to be radically altered, with the axe coming down on big schemes such as this.

Why? If you listen to energy minister Greg Barker, it's because the project was meant to kickstart homeowners or the odd supermarket putting panels on the roof, not encourage "hot money" from the City to build huge arrays. But the real reason for the cutbacks is that demand has been too strong; the policy has been too successful – and costly.

A review of the feed-in tariff is under way and a decision – probably to restrict full, or even all, payments to schemes smaller than 50kW – is about to be announced. So: no hot money, no solar arrays and fewer lower-carbon plants. All this from those who promised to build the greenest government yet.